[R-sig-eco] Bray-Curtis for more than pairwise overlap

[Jarrett Byrnes]

As implemented in the literature, Bray-Curtis dissimilarity measures are used to look at pairwise comparisons.  So, how dissimilar are 2 plots in their composition, for example.

I'm wondering if anyone has run across or implemented a method to look at BC dissimilarity or otherwise that has two different twists to it
	1) Negative values are possible.
	2) The index is for an n-wise measure of dissimilarity.  For example, instead of asking how dissimilar 2 plots are, what is the dissimilarity between 3 plots.

I've been trying to play with vegdist to see if I can implement this, and have been rolling my own functions that work well with just presence-abscence data.  But I'm unclear of how to do so for continuous data.  Thanks!

-Jarrett